How to determine whether it is an array in php

In PHP, array is a very common data type. Determining whether a variable is an array is one of the problems we often encounter. This article will introduce how to determine whether a variable is an array in PHP, and how to determine the array.

1. Use the is_array() function to determine the array

PHP provides an is_array() function, which is used to determine whether a variable is an array. The usage is as follows:

$myArray = array('apple', 'banana', 'orange');
if (is_array($myArray)) {
    echo '变量 $myArray 是一个数组';
} else {
    echo '变量 $myArray 不是一个数组';
}

In the above code, an array $myArray is first defined, and the is_array() function is used to determine whether it is an array. If it is an array, output "Variable $myArray is an array", otherwise output "Variable $myArray is not an array". In addition, the is_array() function can also be used as a condition in the judgment statement, as shown below:

if (is_array($myArray)) {
    // 如果 $myArray 是一个数组，则执行此处代码
}

2. Use the gettype() function to judge the array

In addition to using is_array() In addition to the function judging arrays, you can also use the gettype() function to get the type of a variable, and judge whether it is an array by judging whether the type is "array". The usage is as follows:

$myArray = array('apple', 'banana', 'orange');
if (gettype($myArray) == 'array') {
    echo '变量 $myArray 是一个数组';
} else {
    echo '变量 $myArray 不是一个数组';
}

In the above code, an array $myArray is first defined, and its type is obtained using the gettype() function. Then determine whether the type is "array", if so, output "Variable $myArray is an array", otherwise output "Variable $myArray is not an array".

It should be noted that the return value of the gettype() function not only includes "array", but also "boolean", "integer", "double", "string", "resource", "NULL" and "unknown type". Therefore, if you use the gettype() function to determine whether a variable is an array, you need to pay attention to determine whether the return value is "array".

3. Use isset() function to check array

In PHP, you can use isset() function to check whether a variable is set and not NULL. The isset() function returns false if a variable has not been set or is set to NULL, otherwise it returns true. Therefore, you can use the isset() function to determine whether a variable is an array. The method is as follows:

$myArray = array('apple', 'banana', 'orange');
if (isset($myArray) && is_array($myArray)) {
    echo '变量 $myArray 是一个数组';
} else {
    echo '变量 $myArray 不是一个数组';
}

In the above code, first use the isset() function to check whether the variable $myArray is set and not NULL. Then use the is_array() function to determine whether $myArray is an array. If variable $myArray is set and is an array, output "Variable $myArray is an array", otherwise output "Variable $myArray is not an array".

It should be noted that when using the isset() function to determine whether a variable is set, a "notice" level warning will be generated if the variable is not set. You can use the @ symbol to shield this warning, as follows Shown:

if (@is_array($myArray)) {
    // 检查 $myArray 是否是一个数组
}

4. Use the count() function to determine the array

The count() function in PHP can return the number of elements in an array. If a variable is not an array, the count() function returns 1. Therefore, you can use the count() function to determine whether a variable is an array, as shown below:

$myArray = array('apple', 'banana', 'orange');
if (count($myArray) > 1) {
    echo '变量 $myArray 是一个数组';
} else {
    echo '变量 $myArray 不是一个数组';
}

In the above code, an array $myArray is first defined, and the count() function is used to obtain the number of elements. Then determine whether the number of elements is greater than 1. If so, output "Variable $myArray is an array", otherwise output "Variable $myArray is not an array".

It should be noted that when using the count() function to check whether a variable is an array, since non-array variables will also return 1, it is necessary to determine whether the number of elements is greater than 1.

Summary

In PHP, determining whether a variable is an array is a very common operation. This article introduces four judgment methods, including is_array(), gettype(), isset() and count(). Use these methods to easily determine whether a variable is an array. It should be noted that when using the above method to determine whether a variable is an array, other factors need to be considered to avoid errors.

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